[PATCH net-next v2 13/18] net: macb: avoid double endianness swap in macb_set_hwaddr()

[Sean Anderson]

On 6/27/25 05:08, Théo Lebrun wrote:
> writel() does a CPU->LE conversion. Drop manual cpu_to_le*() calls.
> 
> On little-endian system:
>  - cpu_to_le32() is a no-op (LE->LE),
>  - writel() is a no-op (LE->LE),
>  - dev_addr will therefore not be swapped and written as-is.
> 
> On big-endian system:
>  - cpu_to_le32() is a swap (BE->LE),
>  - writel() is a swap (BE->LE),
>  - dev_addr will therefore be swapped twice and written as a BE value.
> 
> This was found using sparse:
>    ⟩ make C=2 drivers/net/ethernet/cadence/macb_main.o
>    warning: incorrect type in assignment (different base types)
>       expected unsigned int [usertype] bottom
>       got restricted __le32 [usertype]
>    warning: incorrect type in assignment (different base types)
>       expected unsigned short [usertype] top
>       got restricted __le16 [usertype]
>    ...
> 
> Fixes: 89e5785fc8a6 ("[PATCH] Atmel MACB ethernet driver")
> Signed-off-by: Théo Lebrun <theo.lebrun at bootlin.com>
> ---
>  drivers/net/ethernet/cadence/macb_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> index 578e72c7727d4f578478ff2b3d0a6316327271b1..34223dad2d01ae4bcefc0823c868a67f59435638 100644
> --- a/drivers/net/ethernet/cadence/macb_main.c
> +++ b/drivers/net/ethernet/cadence/macb_main.c
> @@ -265,9 +265,9 @@ static void macb_set_hwaddr(struct macb *bp)
>  	u32 bottom;
>  	u16 top;
>  
> -	bottom = cpu_to_le32(*((u32 *)bp->dev->dev_addr));
> +	bottom = *((u32 *)bp->dev->dev_addr);
>  	macb_or_gem_writel(bp, SA1B, bottom);
> -	top = cpu_to_le16(*((u16 *)(bp->dev->dev_addr + 4)));
> +	top = *((u16 *)(bp->dev->dev_addr + 4));>  	macb_or_gem_writel(bp, SA1T, top);
>  
>  	if (gem_has_ptp(bp)) {
> 

Reviewed-by: Sean Anderson <sean.anderson at linux.dev>